MAKING
3. In a 6-quart kettle, place chicken at the bottom and add 3 cups water, the celery, parsley, carrot, onion, salt, peppercorns and bay leaf; heat until the mixture starts to boil, then reduce the heat, cover and simmer for about 1 hour until chicken is tender.
4. Spoon chicken and keep aside in a bowl.
5. Using a strainer, filter the stock and return the stock to the kettle; heat until the stock boils and then boil gently for about 30 minutes until it is reduced to 2 cups.
6. Separate chicken meat from bones in large pieces; should be about 6 cups and keep aside.
7. In a large saucepan, melt butter and remove the pan from heat.
8. Stir in flour, salt, nutmeg and red pepper until smooth.
9. Gradually add milk and 2 cups of stock; stir constantly and bring liquids to boiling.
10. Stir and boil gently for 2 minutes until the sauce thickens slightly.
11. In a small bowl, beat egg yolks and cream; add a little hot mixture and beat gently.
12. Return the egg mixture to the saucepan and cook over low heat with constant stirring until the sauce is hot; do not let the sauce boil.
13. Remove the pan from heat and stir in sherry.
14. Following directions on the package, cook spaghetti and drain.
15. In a kettle, place the cooked spaghetti and add 2 cups sauce; toss until well blended.
16. Separate 2 cups of the sauce, cover and refrigerate.
17. Add the remaining sauce to the chicken and mushrooms.

FINALISING
18. Into two 12x8x2 inch baking dishes, divide the spaghetti equally and spread it around the edges.
19. Spoon equal quantity of chicken mixture at the centre of each dish and sprinkle 2 cups cheese over spaghetti in each dish.
20. Cover the dish with foil and refrigerate.
21. Place the dish covered in the oven, and bake for 30-45 minutes until piping hot.
22. Just before serving, reheat the reserved sauce .